/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.heron.streamlet.impl.streamlets;

import java.util.Set;

import org.apache.heron.api.topology.TopologyBuilder;
import org.apache.heron.streamlet.impl.StreamletImpl;
import org.apache.heron.streamlet.impl.sinks.LogSink;

/**
 * LogStreamlet represents en empty Streamlet that is made up of elements from the parent
 * streamlet after logging each element. Since elements of the parents are just logged
 * nothing is emitted, thus this streamlet is empty.
 */
public class LogStreamlet<R> extends StreamletImpl<R> {
  private StreamletImpl<R> parent;

  public LogStreamlet(StreamletImpl<R> parent) {
    this.parent = parent;
    setNumPartitions(parent.getNumPartitions());
  }

  /**
   * Connect this streamlet to TopologyBuilder.
   * @param bldr The TopologyBuilder for the topology
   * @param stageNames The existing stage names
   * @return True if successful
   */
  @Override
  public boolean doBuild(TopologyBuilder bldr, Set<String> stageNames) {
    setDefaultNameIfNone(StreamletNamePrefix.LOGGER, stageNames);
    bldr.setBolt(getName(), new LogSink<R>(),
        getNumPartitions()).shuffleGrouping(parent.getName(), parent.getStreamId());
    return true;
  }
}
